Structure and thermal stability of melt spun and mechanically alloyed Cu47Ti34Zr11Ni8 and Cu47Ti34Sn11Ni8 alloys

Two applied samples preparation techniques (rapid quenching from the melt and mechanical alloying) resulted in the formation of fully amorphous Cu47Ti34Zr11Ni8 and Cu47Ti34Sn11Ni8 alloys. However, a significant differences in thermal stability and crystallization behaviour have been found, depending not only on the alloy composition, but on the fabrication method as well. MA powders of both alloys studied revealed one dominating DSC exothermic effect. Zr-containing ribbon showed four exothermic effects, while Sn-containing one - only two overlapping peaks. In the case of ribbons it was found that replacing Zr by Sn did not influenced the crystallization temperature or supercooled liquid region, however, the activation energy of crystallization increased significantly, from 190 to 223 kJmol(-1). Opposite behaviour was observed for MA powders. Introducing Sn into the alloy instead of Zr resulted in a considerably increase of the crystallization temperature (from 783 to 826 K), simultaneously the activation energy for crystallization remained the same.